JPS589155Y2 - Dental water heater heater circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heater circuit for a dental water heater installed in a dental unit and used to heat water supplied to a water supply nozzle, a dental syringe, or the like.

Generally, this type of dental water heater is connected to a water supply circuit that supplies water to the water supply nozzle or dental syringe from the tap, and energizes the internal heater to heat the water during dental treatment. The water in the container is heated and the heated water is supplied to a water supply nozzle, dental syringe, etc.

By the way, this is not a problem while the dental water heater is in use, but when the water heater is not in use at night in a cold region, the water in the water heater freezes, and the volume expansion caused by the freezing causes damage to the water heater. This caused the inconvenience that treatment work was impossible.

Therefore, the present invention is intended to solve the above-mentioned inconveniences, and its embodiment will be explained below with reference to the drawings. R1 is a heater for boiling water, and this heater R1 and power source E are connected to changeover switches S1 and S2 for two circuits. are connected via terminals a1., and switch S1 is connected to terminal a1. a1' side and switch S2 is connected to terminal a2. When switching to the a2' side, the heater R1 is energized.

Reference numeral 1 designates a protection circuit that controls the amount of power of the heater R0, which includes a thyristor 2 and a phase control section 3 that applies a gate current to the gate G of this thyristor 2 to control switching of the thyristor 2, and the switches S1 and S2. respectively terminal B
l, bl' and b2. It is activated by switching to the b2' side and turning on the protection circuit switch S3.

The thyristor 2 has an anode A connected to a terminal b of the switch S2.
2', the cathode K is connected to the switch S via the switch S3.
A series circuit of the resistor R2, variable resistor R3, and capacitor C1 of the phase control unit 3 is connected to the anode A and cathode K of the thyristor 3, and the diode D1 and trigger diode D2 are A series circuit is connected between the connection point of the variable resistor R3 and the capacitor C1 and the gate G of the thyristor 2, and the variable resistor R
By varying variable resistor R3 and capacitor C
The firing phase angle of the thyristor 2 is controlled via the trigger diode D2 by a time constant determined from 1 and 1.

Reference numeral 4 denotes an erroneous firing prevention circuit for the thyristor 2, which is composed of a series circuit of a resistor R4 and a capacitor C2, and is connected to the anode A and the cathode of the thyristor 2.

5 is a noise prevention coil connected in series to the cathode K of the thyristor 2, C3 is a noise prevention capacitor, 6 is a pilot lamp, R5 is a protective resistor for the pilot lamp 6, and 7 and 8 are fuses.

Therefore, when using the dental water heater, switches S1 and S2 are connected to terminals a, , a, ' and a2, respectively, as shown in the drawing.
．． When switched to the 2' side, a regular current is supplied to the heater R1, and the water in the water heater is heated to the required temperature by the heating of the heater R1.

Next, when the dental water heater is not in use, switches S1 and S2 are connected to terminals b, b1' and b2, respectively. At the same time, switch S3 is turned on.

Then, a current flows to the capacitor C1 via the resistors R2 and R3, charging the capacitor C1, and this charging voltage causes a gate current to flow to the gate G of the thyristor 2 via the trigger diode D2, making the thyristor 2 conductive. An anode current flows between the anode A and the cathode, and this anode current heats the heater R1. The power consumption of the heater R1 can be reduced by changing the firing phase angle of the thyristor 2 by varying the variable resistor R3. be adjusted.

Therefore, at night when the water heater is not in use, it is possible to prevent the water in the water heater from freezing by varying the variable resistor R3 in accordance with the expected outside temperature.

Note that when the protection circuit 1 is not required, the switches S1 and S2 are connected to the terminals bl, bl' and b2 . It is sufficient to turn off the protection circuit switch S3' while switching to the b2' side.

As described above, according to the present invention, the heater circuit in the water heater is provided with a protection circuit consisting of a thyristor and a phase control section that adjusts the firing phase angle of the thyristor, and this protection circuit is installed in the heater circuit as appropriate. Since it is equipped with a changeover switch for connection, it is convenient to be able to select whether or not to use the protection circuit via the switch, and the use of the protection circuit prevents the water heater from getting damaged due to freezing. be able to,
Furthermore, since a thyristor is used, there are advantages such as less power loss due to the heater.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of the present invention. In the diagram, R1 is a heater, R2 is a resistor, R3 is a variable resistor, and C
1 is a capacitor, Dl is a diode, D2 is a trigger diode, Sl, S2. S3 is a switch, al, a□'
. 1) z, 1) t', az, az', b2. b
2' is a terminal, 1 is a protection circuit, 2 is a thyristor, and 3 is a phase control section.

Claims (1)

[Scope of utility model registration request] For dental use, the heater circuit of a water boiler is equipped with a protection circuit consisting of a thyristor, a phase control section that controls the firing phase angle of the thyristor, and a changeover switch that connects the protection circuit to the heater circuit. Water boiler heater circuit.